Not a problem. I do this weekly (which is as often as I need to charge at the moment). In my garage at home the Mitsu charge cable plugs into a UK 13A "mouth organ" where I have replaced the plug with a good quaity continental plug. Out and about, I have a much smaller version which is UK 3-pin rubber socket wired onto the cable and moulded plug that I curt off a redundant kettle.
I'm really sorry to be pedantic but could you please explain yourself more clearly? I don't understand what you mean by UK 13A "mouth organ". Using slang or jargon is all very well if everyone knows what it means but becomes very muddled if you don't. I think your post is extremely useful, but if you could please explain your actual setup clearly and concisely so a dummy like me can understand what you're on about, I would be extremely grateful and appreciative.